KENNEDY SPACE CENTER, FLA. -- In the white room on Launch Pad 39A, Mission STS-117 Commander Rick Sturckow gives a thumbs up as he prepares to enter Space Shuttle Atlantis. The STS-117 crew practices for launch with a simulation of activities, from suit-up to countdown in the orbiter during terminal countdown demonstration test activities. The STS-117 mission is No. 21 to the International Space Station. Mission payloads aboard Atlantis include the S3/S4 integrated truss structure, a third set of solar arrays and batteries. The crew of six astronauts will install the truss to continue assembly of the station. Launch is scheduled for no earlier than March 15. Photo credit: NASA/Jim Grossman.